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Linkages Between Climate Change and Biodiversity in New Zealand

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Linkages Between Climate Change and Biodiversity in New Zealand Linkages Between Climate Change and Biodiversity in New Zealand Matt McGlone Landcare Research PO Box 69, Lincoln 8152 New Zealand Landcare Research Contract Report: LC0102/014 PREPARED FOR: Ministry for the Environment PO Box 10 362, Wellington New Zealand DATE: September 2001 2 Reviewed by: Approved for release by: Phil Hart David Penman Programme Leader former Science Manager Landcare Research Biodiversity © Landcare Research New Zealand Ltd 2001 No part of this work covered by copyright may be reproduced or copied in any form or by any means (graphic, electronic or mechanical, including photocopying, recording, taping, information retrieval systems, or otherwise) without the written permission of the publisher. 3 Contents Summary.....................................................................................................................................5 1. Introduction .......................................................................................................................7 2. Background .......................................................................................................................7 3. Objectives..........................................................................................................................8 4. Recent and Projected Future Climate Change in New Zealand ........................................8 4.1 Recent changes.........................................................................................................8 4.2 Projected change in New Zealand............................................................................8 5. New Zealand Biodiversity.................................................................................................9 5.1 What is biodiversity? ...............................................................................................9 5.2 Current state of New Zealand biodiversity ............................................................10 5.3 Factors reducing biodiversity.................................................................................10 5.4 Value of biodiversity..............................................................................................11 6. Timescales, Climate Change and Biodiversity................................................................11 6.1 Long-term climate change effects on biodiversity.................................................12 6.2 Short-term climate change and biodiversity ..........................................................13 Current biotic response to climate change..............................................13 7. Predicted Biodiversity Changes in the Short Term .........................................................14 7.1 Predictive models and empirical relationships.......................................................14 7.2 Range and distribution changes .............................................................................16 Lowland plants........................................................................................16 Freshwater species ..................................................................................16 Alpine zone.............................................................................................17 Management implications of range changes...........................................18 7.3 Ecosystem functioning changes.............................................................................19 8. Biodiversity Effects of Changing Climate Extremes ......................................................19 9. Climate Change Interactions with other Factors Affecting Biodiversity ........................21 9.1 Predation by introduced mammals and invertebrates ............................................21 9.2 Herbivory ...............................................................................................................22 9.3 Competitive replacement by exotic species...........................................................22 9.4 Loss of specialised pollinators and dispersers .......................................................23 9.5 Habitat loss.............................................................................................................23 9.6 Fire .........................................................................................................................24 9.7 Fragmentation ........................................................................................................24 9.8 Nutrient changes ....................................................................................................25 9.9 Toxins and herbicides ............................................................................................25 10. Biodiversity and Greenhouse Gas Mitigation Strategies ...............................................25 Landcare Research 4 11. Links with International Frameworks and Activities .....................................................27 12. Conclusions and Recommentations................................................................................28 12.1 Research needs.......................................................................................................28 12.2 Policy recommendations........................................................................................29 13. Acknowledgements .........................................................................................................30 14. References .......................................................................................................................30 5 Summary The following advice to Government on linkages between biodiversity and climate change was prepared by Landcare Research, Lincoln, for the Ministry for the Environment in June – August 2001. 1. There is a strong possibility that the climate of New Zealand will change substantially over the next 100 years, and this will inevitably impact on indigenous biodiversity and ecosystem functioning through the direct effect of increased atmospheric carbon dioxide concentration, warming, precipitation changes and alteration of the frequency and severity of extreme events. 2. Quantitative prediction of climate change for prescribed greenhouse gas emission scenarios through General Circulation Models at a both global and regional level is imprecise and unlikely to improve in the foreseeable future. Effects of climate change on ecological processes are also only approximately reproduced in current models. Nevertheless, these modelling approaches are crucial to understanding the nature of changing climates, approximate magnitudes of ecological effects, and potential management responses. 3. Anthropogenic climate change impacts are certain to last at least 500 years into the future, and probably the earth has entered a permanent warm state. Consideration of long-term (~120 000 years) as well as medium-term (~500 years) timescales should be incorporated into biodiversity planning. 4. There have been few documented effects on the indigenous biota of the approximately 0.7o C increase of mean annual temperature since the turn of last century, and alterations in the mean atmospheric circulation over New Zealand. However, numerous ecological reactions to extreme climatic events have been observed. 5. Climate change is likely to impact on the indigenous biota and their ecosystems over the next 100 years. Four main classes of change are possible: (i) alteration of latitudinal and altitudinal ranges with movement of species and communities southwards and upwards, accompanied by disruptive transitions; (ii) strong impacts on biota and ecosystems already under stress if extreme weather events become more frequent and severe; (iii) changes to productivity and nutrient cycling within ecosystems due to a combination of climate change and carbon dioxide increases; (iv) disruption of freshwater ecosystems through low flows or drying of stream and rivers and warming of water. 6. Potentially the most serious and pressing problems arise through the interaction of climate change with pre-existing threats to the biota. The most important involve pest and weeds, and the following outcomes are likely: (i) establishment of more invasive and damaging pests and weeds; (ii) further expansion southwards of already present exotic organisms; (iii) climate fluctuations changing the food supply of herbivores and omnivores such as rabbits, rats and mice, with flow-on effects on abundance of Landcare Research 6 predators of indigenous vertebrates such as cats, stoats, and rats, making extreme difficulties for conservation managers. 7. Climate change will have its greatest impact on small patches of fragmented habitat with low resilience, and freshwater systems in modified landscapes, through increasing exotic weed and pest pressure and disrupting ecosystem processes. 8. As climate change mainly impacts through exacerbating pre-existing ecological and biodiversity problems, steps being taken or planned, by conservation managers in a range of organisations, on the basis of other biodiversity threats to an extent deal with the issue. However, future or present climate change is rarely taken into account when biodiversity issues are discussed and strategy formulated. Little thought has been given to the long-term consequences of climate change (or indeed any other degrading factor) for the evolutionary future of the biota. These issues should be explicitly taken into account in decisions made on priorities for both species and ecosystems.
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